The following source code is an example of using the ODBC API with Ada for accessing databases. For a complete database package, check out Pascal Obry's page.
with Win32.Sql; use Win32.Sql;
with Win32.SqlExt; use Win32.SqlExt;
with Interfaces.C; use Interfaces.C;
with Ada.Text_Io; use Ada.Text_Io;
with Ada.Unchecked_Conversion;
with System;
pragma Linker_Options("-lodbc32");
procedure Odbcex is
function To_Puchar is new Ada.Unchecked_Conversion (System.Address,
Win32.Puchar);
Odbcexception : exception;
Odbc_Handle_Env : aliased Henv;
Odbc_Connect_Handle : aliased Hdbc;
Odbc_Statement_Handle : aliased Hstmt;
procedure Rok ( Retvalue : Retcode ) is
begin
if Retvalue /= Sql_Success then
raise Odbcexception;
end if;
exception
when E : others =>
Put("ODBC Error: ");
declare
Sql_State : Win32.Puchar;
Sql_Native_Error : aliased Sdword;
Errormsg : Char_Array ( 1 .. 255);
Msgsize : aliased Sword;
Tempvalue : Retcode;
begin
Tempvalue := Sqlerror(Odbc_Handle_Env, Odbc_Connect_Handle, Odbc_Statement_Handle,
Sql_State, Sql_Native_Error'access, To_Puchar(Errormsg'Address), 255, Msgsize'access);
Put_Line(To_Ada(Errormsg));
raise;
end;
end;
ConnectString : Char_Array := To_C("DSN=AdaTest2");
QueryString : Char_Array := To_C("Select * from CallList");
RetString : Char_Array(1..255);
RetLength : aliased Sword;
Retvalue : Retcode;
Numcols : aliased Sword;
Retsize : aliased Sdword;
begin
Rok( Sqlallocenv(Odbc_Handle_Env'access) );
Rok( Sqlallocconnect(Odbc_Handle_Env, Odbc_Connect_Handle'access) );
Rok( Sqldriverconnect( Odbc_Connect_Handle, System.Null_Address,
To_puchar(connectstring'Address), Sql_Nts,
To_puchar(Retstring'Address), 255, Retlength'access,
Sql_Driver_Complete) );
Rok( Sqlallocstmt(Odbc_Connect_Handle, Odbc_Statement_Handle'access) );
Rok( Sqlprepare(Odbc_Statement_Handle, To_puchar(QueryString'Address), Sql_Nts) );
Rok( Sqlexecute(Odbc_Statement_Handle) );
Rok( Sqlnumresultcols ( Odbc_Statement_Handle, Numcols'access ) );
loop
Retvalue := Sqlfetch( Odbc_Statement_Handle);
exit when Retvalue /= Sql_Success;
for I in 1 .. Numcols loop
Rok( Sqlgetdata ( Odbc_Statement_Handle, UWORD(I), Sql_C_Char, Retstring'Address, 254, Retsize'access ) );
Put("|");
if RetSize>0 then
Put( To_Ada(Retstring(1..size_t(RetSize)), False) );
end if;
Put("|");
end loop;
New_Line;
end loop;
Rok( Sqlfreestmt(Odbc_Statement_Handle, Sql_Drop) );
Rok( Sqldisconnect(Odbc_Connect_Handle) );
Rok( Sqlfreeconnect(Odbc_Connect_Handle) );
Rok( Sqlfreeenv(Odbc_Handle_Env) );
end Odbcex;
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